Let's calculate the mean of the 5 lunches in the first week. We calculate the mean by adding all the numbers up and dividing by how many numbers there are. So we have:
[tex]\sf\dfrac{12.48+9.50+10.25+4.99+8.59}{5}=9.162[/tex]
So this is the mean of the 5 lunches in the first week. We are told that in the second week he spent $3 more on his 5 lunches, let's calculate the mean of the second week:
[tex]\sf\dfrac{12.48+9.50+10.25+4.99+8.59+3}{5}=9.762[/tex]
This is the mean for the second week. Subtract it from the mean in the first week to find the increase:
[tex]\sf 9.762-9.162=\boxed{\sf\$ 0.60}[/tex]
